Multi-Channel Imaging Devices

ABSTRACT

A multi-channel imaging device is provided. The multi-channel imaging device comprises a focal plane array comprising an array of pixels configured to detect radiation in a predetermined wavelength band. Subsets of the array of pixels are arranged to define a plurality of unit cell image areas. The multi-channel imaging device also comprises a lens array comprising a plurality of lens elements configured to image a scene onto the plurality of unit cell image areas. The lens elements and the unit cell image areas define a plurality of unit cells comprising at least one lens element and at least one unit cell image area. Each of the plurality of unit cells is configured to create a complete image of the scene. Additionally, a plurality of unit cell filters corresponding to the plurality of unit cells is configured to filter radiation such that each unit cell is dedicated to an image channel is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/364,164, filed on Feb. 2, 2009 and entitled “Multi-Channel ImagingDevices.”

TECHNICAL FIELD

Embodiments of the present disclosure relate to imaging devices, andmore particularly, to compact multi-channel imaging devices.

BACKGROUND

Forward looking infrared (FLIR) sensors are imaging devices that detectinfrared radiation to create an image of a scene. FLIR sensors commonlyutilize a two dimensional array of pixels such as a focal plane array(FPA) to form the infrared image. The pixels of infrared FPAs, forexample, are formed of a material that is sensitive to infraredradiation, such as indium antimonide (InSb), Mercury Cadium Telluride(MCT), or other infrared-sensitive materials. FLIR sensors are typicallyconfigured to operate within long-wave infrared (e.g., 8-14 μm) andmid-wave infrared (e.g., 3-5 μm) bands. Infrared light is focused ontothe pixels of the FPA which then generate a signal such as a voltagethat corresponds to the level of infrared light detected. The signalsgenerated by the pixels may then be sent to other internal or externalsystem electronics to be compiled into a thermal image of the scene. Asmany infrared FPAs operate most effectively at very cold temperatures,the FPAs of FLIR sensors are commonly cryogenically cooled within adewar flask.

Particular FLIR sensors may be configured to filter infrared radiationto a particular channel. For example, a FLIR sensor may incorporate afilter that provides either multi-spectral (i.e., Red, Green and Blueregions of a nominal wavelength band under detection), polarimetric orpanchromatic filtering. Multi-spectral and polarimetric imagery utilizethe comparison of the images from each channel, and therefore requireaccurate image registration to prevent false signals. Therefore,simultaneous capture of multi-spectral and polarimetric imagery isrequired. Under current FLIR design, a single FLIR sensor is eitherdedicated to one particular channel by a single passband filter, or isfiltered at the individual pixel level, which requires very small filterpatterns at the pixel pitch dimension. Such small filters or smallfilter patterns are difficult and expensive to manufacture and implementin a FLIR sensor. Additionally, requiring at least one FLIR sensor forimaging in each desired channel adds significant weight to the imagingsystem, should simultaneous capture of multi-spectral and polarimetricimagery be desired.

FLIR sensors or cameras are utilized in many applications, includingtarget acquisition in naval vessels and aircraft, surveillance, searchand rescue, and use on unmanned aerial vehicles (UAVs). Particularly,FLIR sensors require technology for high-resolution imagery withcontrast enhancement for better target identification. Further, someapplications, such as those aboard an UAV, which are commonly extremelylight and cannot carry significant weight, require FLIR sensors thatprovide for high-resolution imagery and low noise attributes in apackage of very low mass and volume. Therefore, high-resolution imageryin such applications should be achieved with the use of minimal,lightweight components.

SUMMARY

Accordingly, it is against this background that compact, multi-channelimaging devices that provide high-resolution imagery with broadbandpanchromatic, multi-spectral and polarimetric content in a singlepackage are desired.

According to one embodiment, a multi-channel imaging device is provided.The multi-channel imaging device includes a focal plane array comprisingan array of pixels configured to detect radiation in a predeterminedwavelength band. Subsets of the array of pixels are arranged to define aplurality of unit cell image areas. The multi-channel imaging devicealso includes a lens array comprising a plurality of lens elementsconfigured to image a scene onto the plurality of unit cell image areas.The lens elements and the plurality of unit cell image areas define aplurality of unit cells, each unit cell comprising at least one lenselement and at least one unit cell image area. Each of the unit cells isconfigured to create a complete image of the scene. Additionally, aplurality of unit cell filters corresponding to the plurality of unitcells is configured to filter radiation corresponding to the scene suchthat each unit cell is dedicated to an image channel.

According to another embodiment, a multi-channel imaging device is alsoprovided. According to the embodiment, the multi-channel imaging deviceincludes a plurality of unit cells, each unit cell comprising an arrayof pixels and a lens element. The pixels of the array are configured todetect radiation in a predetermined band. Each unit cell of theplurality of unit cells is configured to generate a complete image of ascene to be combined into at least one multi-channel image, wherein eachunit cell is dedicated to an image channel.

According to yet another embodiment, a multi-channel imaging device isalso provided. According to the embodiment, the multi-channel imagingdevice includes a plurality of unit cells, each unit cell is dedicatedto an image channel and configured to generate a complete image of ascene. Each unit cell comprises an array of pixels capable of detectingradiation in a predetermined band, and a lens element configured toimage the complete image onto the array of pixels and arranged having anoffset relative to the array of pixels within the unit cell such thatthere is a sub-pixel shift of the complete image relative to thecomplete image of adjacent unit cells.

According to yet another embodiment, a method of generatingmulti-channel imagery of a scene is provided. The method includesreceiving a plurality of complete images of the scene from amulti-channel imaging device. The multi-channel imaging device includesa plurality of unit cells, wherein each unit cell includes an array ofpixels and a lens element. The pixels are configured to detect radiationin a predetermined wavelength band. Each unit cell is configured togenerate a complete image of the scene and is dedicated to an imagechannel. The method further includes combining the plurality of completeimages provided by the plurality of unit cells, thereby generatingmulti-channel imagery of the scene.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description will be more fully understood in viewof the drawings in which:

FIG. 1 is a schematic illustration of a cross sectional view of aportion of an exemplary multi-channel imaging device according to one ormore embodiments;

FIG. 2 is a schematic illustration of a plurality of exemplary unitcells and offset images focused thereon according to one or moreembodiments;

FIG. 3 is a schematic illustration of four exemplary filtered unit cellsaccording to one or more embodiments;

FIG. 4 is a schematic illustration of four exemplary filtered unit cellsaccording to one or more embodiments; and

FIG. 5 is a schematic illustration of a cross sectional view of aportion of an exemplary multi-channel imaging device according to one ormore embodiments.

The embodiments set forth in the drawings are illustrative in nature andare not intended to be limiting of the invention defined by the claims.Moreover, individual features of the drawings and the invention will bemore fully apparent and understood in view of the detailed description.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the present disclosure relate to multi-channel imagingdevices. More specifically, embodiments may provide high-resolutioninfrared imagery with broadband panchromatic intensity levels,multi-spectral content, as well as range and polarimetric informationfor enhanced object discrimination and identification utilizing a singlefocal plane array (FPA). Further, particular embodiments also increasethe size and decrease the complexity of filters used to filter imagecontent, thereby reducing manufacturing and production costs. Accordingto some embodiments, a sub-pixel parallax may be utilized to yieldhigh-resolution imagery, provide for range estimates of targets, anddiscriminate a moving object from background clutter.

Referring to FIG. 1, as well as FIGS. 2-4, a portion of an exemplaryimaging device 100 (such as a compact, cooled FLIR camera, for example)is illustrated. It is noted that the term camera and sensor may beutilized interchangeably herein. According to some embodiments, thecamera may operate in the mid-wave infrared band. It is alsocontemplated that, although embodiments of the present disclosure aredescribed herein in the context of infrared imaging devices, embodimentsmay also be configured for detection in other wavelength bands, such asin the visible wavelength band, for example. The exemplary device 100comprises a focal plane array 20 having a plurality of pixels arrangedin an array, a lens array 10 comprising multiple lens elements (e.g.,12, 14, and 16) arranged in a plane, and appropriate lens elementbaffling 11. A plurality of unit cells 30 comprising a single lenselement (e.g., lens element 14) and an image area 32 defined by arectangular portion of the focal plane array 20 (see FIGS. 2-4) create afull image of a scene, object or target. The image area 32 comprises asubset of pixels 34 of the focal plane array 20. A unit cell 30 may bedefined as the components positioned between dashed lines A and B.

The pixels 34 (see FIGS. 2-4) of the pixel array 20 may be configured asdiodes comprising a material capable of detecting radiation in theinfrared wavelength region (i.e., a predetermined wavelength band), suchas indium antimonide (InSb), and may be formed on a support substrate(not shown) by reticulation or any other currently known oryet-to-be-developed process. The pixels 34 may provide a signal orsignal value such as a voltage that corresponds to the level ofradiation detected. For example, when a pixel detects a high level ofinfrared radiation, it may provide a voltage that is higher than a pixelthat detects a low level of infrared radiation. The signals provided bythe pixels of the unit cells make up a complete image of the scene.

Each image area 32 may comprise a subset array of pixels 34 of the focalplane array 20. For example, as illustrated in FIGS. 2-4, the pixels 34may be arranged within each image area 32 by rows and columns. AlthoughFIGS. 2-4 illustrate each image area 32 of the unit cell 30 having rowsand columns of three pixels 34 each for a total of nine pixels 34, anynumber of pixels 34 may be utilized within each image area 32.

The lens array 10 may be positioned within a dewar flask in a plane thatis in front of the focal plane array 20 with respect to the path ofradiation (e.g., 50) entering the sensor 100. Each lens element 12, 14,16 of the array may be positioned and secured within the dewar flask byany type of baffling 11, which may comprise, by way of example and notby way of limitation, a pinhole mask boresighted to each lens element.The lens elements 12, 14, 16, which may be micro lenses according tosome embodiments, may be sized according to the desired size of eachunit cell 30. The lens array 10 may be fabricated by methods known tothose skilled in the art or any yet-to-be developed methods. By way ofexample and not limitation, the lens elements 12, 14, 16, of the lensarray 10 may comprise plano-convex lenses etched into a silicon wafer byphoto-lithography methods.

The lens elements 12, 14, 16 may be objective lenses that focus acomplete image of the scene, target or object upon the pixels 34 of eachimage area 32. FIG. 2 is a schematic representation of an image 40 a-ffocused onto six exemplary image locations 32 a-f. It is noted that onlysix image areas 32 a-f are illustrated for simplicity and embodiments ofthe multi-channel imaging devices 100 disclosed herein may comprise manymore unit cells 30. Each unit cell 30 is configured to provide aseparate and complete image 40 a-f of the same scene, target or object.As described hereinbelow, the complete images 40 a-f provided by theunit cells 30 may be collected and combined into a higher resolutionimage or images.

According to some embodiments, the lens elements (e.g., 12, 14, 16 ofFIGS. 1 and 5) are arranged and positioned within the lens array 10 suchthat the location of an image (e.g., 40 a-f of FIG. 2) within each imagearea 32 is offset with respect to the image locations within adjacentimage areas. The center to center spacing of the lenses may be chosensuch that an offset is seen in registering the images relative to theirrespective image of the scene. For example, the location of the image 40a that is focused onto image area 32 a by a particular lens element (notshown) is shifted left of center. The location of image 40 a istherefore offset relative the location of image 40 b within image area32 b, as well as the location of image 40 d within image area 32 d.Similarly, the location of image 40 b is offset from the locations ofimages 40 c and 40 e that are focused upon image areas 32 c and 32 e,respectively, as well as the location of image 40 a within 32 a.According to the illustrated embodiment, the plurality of full images 40a-f are imaged by corresponding lens elements at different locationsupon the image areas 32 a-f with respect to one another. Shifting thelocation of the images 40 a-f in such a manner described above creates aparallax between adjacent image cells 30.

The images 40 may be shifted by an offset value that is less than awidth of one pixel. The sub-pixel image shift described above may beutilized to provide for high resolution imagery. Once the images arecollected, the lower resolution images from each unit cell may berecombined to a higher resolution by image reconstruction algorithms,such as super resolution techniques known in the art, or otheryet-to-be-developed algorithms and techniques. By using the sub-pixelparallax induced image shifts from one unit cell 30 to the next, superresolution algorithms may improve resolution of the images many times toyield high resolution imagery. Offsetting the images 40 enablesincreased detection of high spatial frequency content of objects thatmay be imaged by the imaging device 100. This may be achieved byeffectively sampling the scene at a higher rate than the pixel pitchnominally affords, thereby reducing the aliasing in the image due tohigh spatial frequency content according to the Sampling Theorem.

Referring again to FIG. 2, a complete image 40 b is positioned in thecenter of image area 32 b. The pixel in the center of the image area 32b will provide a relatively large signal value in detecting incomingradiation, while the remaining pixels within image area 32 b willprovide a relatively smaller signal value than the pixel in the centerof image area 32 b. Referring now to image area 32 a, the complete image40 a is shifted to the left by a sub-pixel offset value of approximatelyone-half of a pixel with respect to the location of image 40 b. Thepixel in the center of image area 32 a may still provide a relativelylarge signal value, however, the pixels in the left column within imagearea 32 a will provide larger signal values than those pixels in theleft column of image area 32 b.

Sampling the scene, target or object at multiple image shifts mayprovide more detail in the resulting reconstructed image or images. Forexample, to detect high spatial frequency content within a scene, suchas a building or other manmade structure, the image reconstructionalgorithm may detect small changes between the images provided by theunit cells 30. For example, the image 40 a focused upon image area 32 amay be slightly different than the image 40 b focused upon image area 32b. The detected changes between the images provided by the unit cells 30provide high-resolution detail that may be incorporated into thereconstructed image. The images 40 a-f within image areas 32 a-f of FIG.2 are shifted by approximately one-half of a pixel with respect to oneanother, which may provide approximately twice the resolution of animaging device that does not offset or shift the location of the image.Embodiments that shift the image location by one-quarter of a pixel, forexample, may achieve four times the resolution. The offsets provided bythe lens elements (e.g., 12, 14, 16) of the lens array 10 may be fixedand calibrated for reduced computation time and improved accuracy whenrestoring the higher resolution imagery. Shifting the images asdescribed above may allow for significant resolution improvement in thefinal restored image or images without the need to alter the design ofthe focal plane array 20, thereby reducing the cost and complexity ofthe multi-channel imaging device 100. However, it is contemplated thatthe unit cell 30 configuration and image offsets described hereinabovemay also be utilized in conjunction with other high-resolutiontechniques known to those skilled in the art, or techniques that are yetto be developed.

Image reconstruction or processing algorithms discussed herein may beexecuted by an image processing device or system that may be an integralcomponent of the multi-channel imaging device 100. According to otherembodiments, the multi-channel imaging device 100 may electronicallytransmit data representing the complete images received from theplurality of unit cells 30 to an external or off-site image processingdevice or system configured to reconstruct the plurality of images intomulti-channel imagery. The image processing device or system maycomprise dedicated electronics and software programmed to execute imagereconstruction and processing algorithms. According to otherembodiments, the image processing device or system may comprise ageneral purpose computer that receives the image data from themulti-channel imaging device 100 through an electronic communicationchannel (e.g., satellite or cellular communication channels) andexecutes the image reconstruction and processing algorithms.

Because each unit cell 30 is configured to form a separate and completeimage of the same scene, target or object as described hereinabove, eachunit cell 30 may be filtered to extract a single image channel. Forexample, image channels may comprise, but are not limited to,multi-spectral, panchromatic, polarimetric and spectro-polarimetric.Referring to FIGS. 3 and 5, for multi-spectral filtering, a thin filminterference filter 62 may be deposited directly onto the focal planearray 20, covering a subset of pixels on the focal plane array 20 (i.e.,an image area 32 of a unit cell 30).

The multi-spectral channel may comprise, for example, a red channel, ablue channel or a green channel. The terms red channel, green channeland blue channel herein refer to portions of a nominal band underdetection (e.g., the predetermined wavelength band) and not necessarilythe wavelengths in the red (e.g., ˜600 nm), green (e.g., ˜500 nm) andblue (e.g., ˜400 nm) regions of the visible spectrum. By way of exampleand not limitation, if the FPA pixels are configured to detect radiationin the 1 μm to 5 μm wavelength range, the red channel may be 1-2 μm, thegreen channel 2-3 μm and the blue channel 4-5 μm. According to theembodiment illustrated in FIG. 3, a patterned filter configured tofilter infrared radiation to the red band (i.e., a red channel) isdeposited onto all of the pixels of image area 32 g. FIG. 5 illustratespatterned filters 62 and 64 that are deposited onto the focal planearray 20. Similarly, image area 32 h comprises a filter that filters tothe green band while image area 32 j is dedicated to the blue band.Image area 32 i may be configured as an open band without filtering toextract panchromatic scene imagery with highest signal to noise ratio.The panchromatic image will filter the least amount of light, improvingthroughput and signal levels. Because the unit cells 30 form completeimages of the scene, target, or object, the filters may be increased insize from roughly the pixel pitch dimension to the size of the imagearea 32 of the unit cell 30, which may be many times the pixel pitchdimension. This increased size of the filters reduces manufacturingcomplexities, as well as edge effects both in pattern deposition due toshadowing and in imaging due to diffraction.

Full unit cells 30 may also be dedicated to different polarizationorientations. FIG. 4 illustrates four exemplary image areas 32 k-n ofparticular unit cells 30. Image areas 32 m and 32 n are dedicated to twodifferent, orthogonal polarization orientations. Polarization filteringmay be achieved by applying wire grid polarizers to the focal planearray 20 or to the lens elements (e.g., 12, 14, 16) of the lens array10. Because the wire grid polarizers may cover many pixels rather thansingle, individual pixels, manufacturing costs may be reduced.Additionally, extinction ratios may also be improved by the reduction ofdiffraction effects from the aperture edges of the filter elements.

Unit cells may also be dedicated to a spectro-polarimetric channel,wherein a particular unit cell 30 that is dedicated to a particularspectral band is further filtered for a single polarimetric state.Spectro-polarimetric may be defined as a combination of a multi-spectralchannel and a polarimetric channel. Image area 32 i is dedicated to aspectro-polarimetric channel that comprises both a filter configured tofilter radiation to the green band of the multi-spectral channel as wellas a filter configured to filter radiation to a particular polarizationorientation.

FIG. 5 illustrates a side view of three unit cells 30a-c of an exemplarymulti-channel imaging device 100. Unit cells 30 dedicated to particularchannels may be arranged across the focal plane array 20 in any order orconfiguration that fits the demands of the particular application inwhich the multi-channel imaging device 100 is designed to operate. Unitcell 30 a is configured as open-band for panchromatic imagery, whileunit cell 30 b comprises a wire grid polarizer 60 for polarimetricimagery and unit cell 30 c comprises an interference filter 64 formulti-spectral imagery, which may be dedicated to the red, blue or greenband or channel. Additionally, spectro-polarimetric imagery may beachieved by depositing a wire grid polarizer (e.g., 60) on top of a thinfilm multi-spectral filter (e.g., 62). According to other embodiments,the filters may also be placed on the lens elements themselves to avoidmanufacturing complications in particular focal plane technologies. Afilter deposited on a lens element such as 12, 14, or 16 may be desiredin spectro-polarimetric dedicated unit cells 30, wherein themulti-spectral filter may be deposited on the lens element and themulti-spectral filter deposited onto the focal plane array 20.

Embodiments of the present disclosure enable multi-spectral,polarimetric, spectro-polarimetric, and panchromatic imagery to besimultaneously extracted from a scene by an arrangement of dedicatedunit cells 30 across a single focal plane 20. As described hereinabove,the low resolution unit cell images may be collected and reconstructedto create a high resolution, multi-channel image or images usingconventional and yet-to-be-developed reconstruction algorithms. Forexample, the complete images provided by unit cells dedicated to aparticular channel may be combined into a high resolution image for thatparticular channel, resulting in separate high-resolution images foreach channel. According to other embodiments, all of the complete imagesprovided by the unit cells may be combined into one image such thatcontent for a particular channel may be later extracted.

The complete images provided by the dedicated unit cells 30 may providedetailed information about the scene, target or object that is detected.For example, according to some embodiments, pairs of polarimetricdedicated unit cells with orthogonal polarization orientation, such asunit cells 32 m and 32n illustrated in FIG. 4, may be arranged acrossthe focal plane array 20 to discern man-made objects from naturalobjects within a scene. Comparing the orthogonally polarized imagesallows for the detection of linear polarization by registration betweenthe images for appropriate pixelwise addition and subtraction of therespective polarization states. Additionally, comparing separate imagesin a given band may provide a more complete extraction of scene content.By using an inherent parallax that exists between the individual unitcells dedicated to a particular channel, range estimates of a target maybe calculated and moving objects within a scene may be differentiatedfrom background clutter. Because each unit cell 30 views the same objectfrom a slightly different perspective, parallax is present, where theobject distance, baseline between the unit cells 30 and focal length ofthe lenses determine the relative offset of the object from onesub-image to the next. An algorithm may compare the object location ineach sub-image for multiple time frames to estimate both range andmotion.

It is noted that terms such as “commonly,” and “typically,” if utilizedherein, should not be read to limit the scope of the claimed inventionor to imply that certain features are critical, essential, or evenimportant to the structure or function of the claimed invention. Rather,these terms are merely intended to highlight alternative or additionalfeatures that may or may not be utilized in a particular embodiment ofthe present invention.

For the purposes of describing and defining the present invention it isnoted that the term “approximately” is utilized herein to represent theinherent degree of uncertainty that may be attributed to anyquantitative comparison, value, measurement, or other representation.The term “approximately” is also utilized herein to represent the degreeby which a quantitative representation may vary from a stated referencewithout resulting in a change in the basic function of the subjectmatter at issue.

It is noted that recitations herein of a component of the presentinvention being “programmed” or “configured” in a particular way,“programmed” or “configured” to embody a particular property, orfunction in a particular manner, are structural recitations as opposedto recitations of intended use. More specifically, the references hereinto the manner in which a component is “configured” denotes an existingphysical condition of the component and, as such, is to be taken as adefinite recitation of the structural characteristics of the component.

It is also noted that the use of the phrase “at least one” in describinga particular component or element does not imply that the use of theterm “a” in describing other components or elements excludes the use ofmore than one for the particular component or element. Morespecifically, although a component may be described using “a,” it is notto be interpreted as limiting the component to only one.

The foregoing description of the various embodiments of the inventionhas been presented for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise steps and/or forms disclosed. Many alternatives, modificationsand variations will be apparent to those skilled in the art of the aboveteaching. Moreover, although multiple inventive aspects have beenpresented, such aspects need not be utilized in combination, and variouscombinations of inventive aspects are possible in light of the variousembodiments provided above. Accordingly, the above description isintended to embrace all possible alternatives, modifications,combinations, and variations that have been discussed or suggestedherein, as well as all others that fall with the principles, spirit andbroad scope of the inventions as defined by the claims.

1. A multi-channel imaging device comprising: a focal plane arraycomprising an array of pixels configured to detect radiation in apredetermined wavelength band, wherein subsets of the array of pixelsare arranged to define a plurality of unit cell image areas; a lensarray comprising a plurality of lens elements configured to image ascene onto the plurality of unit cell image areas, wherein: theplurality of lens elements and the plurality of unit cell image areasdefine a plurality of unit cells; each unit cell comprises at least onelens element and at least one unit cell image area; and each unit cellis configured to create a complete image of the scene; and lens elementsof the plurality of lens elements are arranged within the lens arrayhaving an offset relative to a plurality of pixels within the unit cellssuch that there is a sub-pixel shift of the complete image relative tothe complete image provided by adjacent unit cells; a plurality of unitcell filters corresponding to the plurality of unit cells configured tofilter radiation corresponding to the scene such that each unit cell isdedicated to a dedicated image channel, wherein each unit cell filterspans more than one individual pixel; and an image processing devicethat simultaneously extracts one or more low resolution images from oneor more unit cells, and one or more high resolution images from multipleunit cells, wherein the one or more high resolution images are based atleast in part on the offset of the lens elements corresponding to themultiple unit cells.
 2. The multi-channel imaging device as claimed inclaim 1, wherein the dedicated image channel comprises a spectralchannel, a panchromatic channel, a polarimetric channel, or acombination thereof.
 3. The multi-channel imaging device as claimed inclaim 2, wherein the one or more low resolution images is a spectral orpolarimetric image.
 4. The multi-channel imaging device as claimed inclaim 2, wherein the spectral channel comprises a long wavelengthspectral channel configured to detect radiation in a long wavelengthportion of the predetermined wavelength band, a mid-wavelength spectralchannel configured to detect radiation in a mid-wavelength portion ofthe predetermined wavelength band, or a short wavelength spectralchannel configured to detect radiation in a short wavelength portion ofthe predetermined wavelength band.
 5. The multi-channel imaging deviceas claimed in claim 1, wherein the multi-channel imaging devicecomprises at least one pair of adjacent unit cells dedicated to aspectral-polarimetric channel or a polarimetric channel such that apolarization orientation of the radiation filtered by a first unit cellof the at least one pair of adjacent unit cells is orthogonal to apolarization orientation of the radiation filtered by a second unit cellof the at least one pair of adjacent unit cells.
 6. The multi-channelimaging device as claimed in claim 5, wherein the lens element of eachunit cell is configured and positioned to focus the complete image ofthe scene onto the array of pixels at an image location such that thereis a sub-pixel offset between the image location of adjacent unit cells,thereby forming a sub-pixel parallax between complete images provided byadjacent unit cells.
 7. The multi-channel imaging device as claimed inclaim 6, wherein the image processing device detects high spatialcontent of the scene based at least in part on the sub-pixel parallaxbetween the complete images provided by adjacent unit cells.
 8. Themulti-channel imaging device as claimed in claim 7, wherein the imageprocessing device provides range estimation of a target based on thesub-pixel parallax.
 9. The multi-channel imaging device as claimed inclaim 1, wherein one or more unit cell filters of the plurality of unitcell filters are configured such that selected unit cells are dedicatedto a spectro-polarimetric channel.
 10. The multi-channel imaging deviceas claimed in claim 9, wherein the one or more unit cell filters of theplurality of unit cell filters corresponding to the spectro-polarimetricchannel comprise a thin film spectral filter positioned on the focalplane array and a polarimetric filter positioned on the lens element ofthe unit cell.
 11. The multi-channel imaging device as claimed in claim1, wherein one or more unit cell filters of the plurality of unit cellfilters comprise a thin film filter, a wire grid polarizer, or acombination thereof, that is larger than a pixel pitch dimension of thearray of pixels.
 12. The multi-channel imaging device as claimed inclaim 1, wherein the selected ones of the plurality of unit cell filtersare positioned on the focal plane array, the lens elements of the lensarray, or a combination thereof.
 13. A method of generatingmulti-channel imagery of a scene comprising: receiving a plurality ofcomplete images of the scene from a multi-channel imaging devicecomprising a plurality of unit cells, each of the unit cells comprisingan array of pixels configured to detect radiation in a predeterminedwavelength band and a lens element, wherein: each of the unit cells isconfigured to generate a complete image of the scene; and each of theunit cells is dedicated to an image channel; combining selected imagesof the plurality of complete images provided by the plurality of unitcells that correspond to a given channel, thereby generatingmulti-channel image of the scene; and simultaneously providing one ormore of the plurality of complete images and the multi-channel image.14. The method as claimed in claim 13, wherein at least one pair ofadjacent unit cells are dedicated to at least a polarimetric channelsuch that the polarization orientation of radiation filtered by a firstunit cell of the pair of adjacent unit cells is orthogonal to thepolarization orientation of radiation filtered by a second unit cell ofthe pair of adjacent unit cells.
 15. The method as claimed in claim 13,further comprising: comparing the complete images of unit cells that arededicated to a given image channel; obtaining a range estimate of atarget within the scene based at least in part on the comparison of theimages of unit cells dedicated to the given image channel; and detectinglinear polarization of objects within the scene.
 16. The method asclaimed in claim 13 wherein combining the plurality of complete imagesis performed by an image reconstruction algorithm executed by an imageprocessing device.
 17. The method as claimed in claim 13 wherein: thelens element of each unit cell is configured and positioned to focus thecomplete image of the scene onto the array of pixels at an imagelocation such that there is a sub-pixel offset between the imagelocation of adjacent unit cells, thereby forming a sub-pixel parallaxbetween complete images provided by adjacent unit cells; and the methodfurther comprises detecting high spatial content of the scene based atleast in part on the sub-pixel parallax between the complete images ofadjacent unit cells.
 18. The method as claimed in claim 17, whereincomparing the complete images of unit cells dedicated to the given imagechannel further comprises evaluating the sub-pixel parallax between thecomplete images of unit cells dedicated to the given image channel. 19.A method of generating multi-channel imagery of a scene comprising:receiving a plurality of complete images of the scene from amulti-channel imaging device comprising a plurality of unit cells, eachof the unit cells comprising an array of pixels configured to detectradiation in a predetermined wavelength band and a lens element,wherein: each of the unit cells is configured to generate a completeimage of the scene; and each of the unit cells is dedicated to an imagechannel; and the lens element of each unit cell is configured andpositioned to intentionally focus the complete image of the scene ontothe array of pixels at an image location such that there is a sub-pixeloffset between the image location of adjacent unit cells, therebyforming a sub-pixel parallax between the complete images of adjacentunit cells; combining selected images of the plurality of completeimages provided by the plurality of unit cells that correspond to agiven channel, thereby generating multi-channel image of the scene; anddetecting high spatial content of the scene based at least in part onthe sub-pixel parallax between the complete images of adjacent unitcells.
 20. The method as claimed in claim 19, further comprising:comparing the complete images of unit cells that are dedicated to agiven image channel; obtaining a range estimate of a target within thescene based at least in part on the comparison of the images of unitcells dedicated to the given image channel; and detecting linearpolarization of objects within the scene.